1. Field of the Invention
This invention relates to package forming, and more particularly, it pertains to a method of and apparatus for packaging articles in a hose-shaped wrapper.
2. Description of the Prior Art
Net bags have been favorably received in marketing channels for packaging produce, such as citrus fruit, because they improve package appearance and quality maintenance of the produce. The fruit is exposed to air within the net bags and thus can breathe, while in polyethylene film bags, which have also been used in packaging fruit, air circulation is limited even when such bags are provided with special breathing holes. Pre-manufactured net bags, however, cost about twice as much as bags made of polyethylene film and require special equipment for opening and filling. Thus, despite their obvious advantages, they have not been readily accepted by the fruit and produce packaging industry.
Net bagging material, typically of polyethylene, is provided by the manufacturer generally in the form of a long rope of unstretched tubing with the tubing being provided in continuous form on a coil. In order to adapt such material for use with conventional produce filling equipment, the net tubing must first be severed and made into bags and then applied to the prior art equipment with special adaptive devices. As mentioned hereinbefore, this has materially increased the costs of packaging and, hence, has not been readily accepted by the industry. There has been a continuing search for a machine which will handle net tubing in its continuous state and form the bags at the same time that the produce is placed therein. One such machine, as used for the citrus bagging market in Florida, is described in a report by the Agricultural Research Service, U.S. Department of Agriculture, entitled "Automatic Produce-Bagging Machine That Uses Factory-Roll Polyethylene Net Tubing ", ARS-S-18, published July 1973. The machine as described operates in a manner whereby the free end portion of a continuous rope of net tubing is brought up into a gripping head and is arranged to be spread open by a device within the tubing. The gripping head elevates the opened, free end of the tubing into a position to receive a batch of fruit. Then, that portion of the net material which is directly above the spreading means is clamped and cut off. Upon completion of the filling of fruit into the separated portion of the tubing, the top thereof is clamped and the completed and filled bag is released.
Other apparatus for packaging articles into bags formed from a continuous supply of hose-shaped material is shown in various prior art patents. For example, U.S. Pat. No. 2,908,123 of Muller et al, issued Oct. 13, 1959, discloses a device for forming filling, closing and disconnecting packages from a supply of hose-shaped, net packing material that is stretched over a filling tube opening and pulled out in lengths as required for each separate package. While the net packing material extends upwardly along the outer surface of a forming tube, over the upper rim of the tube and downwardly through the tube bore, the filling tube, wherein the articles to be packaged are batched, is a separate tube that is placed inside of the hose-shaped packing material.
U.S. Pat. No. 2,706,370 of Snyder, issued Apr. 19, 1955, discloses an apparatus for forming packages with a continuous supply of flexible tubular wrapping material that extends upwardly along the outer surface of a forming tube, over the upper rim of the tube and downwardly into the tube bore where the product is filled for forming a package. The clamping of the wrapping material to form successive packages is performed at both the top and the bottom of the forming tube.
U.S. Pat. No. 2,292,231 of Lesavoy, issued Aug. 4, 1942, discloses an automatic packaging system wherein a double walled bag is formed about the exterior of a vertically positioned product batching tube. Clamping and cutting means are utilized at the lower end of the tube to successively tie and sever the bags after the deposit of product therein. A gate within the batching tube allows the accumulation of a given quantity of the product while a previously filled bag is being closed and detached.
U.S. Pat. No. 2,656,658 of Grady, issued Oct. 27, 1953, discloses a vertically arranged filling tube for a bag making and filling machine. The free end of a longitudinally-compacted length of tubular material is drawn downward past a pair of crimping elements. An electrically-heated filament loop positioned therebetween is used to close, and detach the filled lower-most bag and to close and provide a platform for the lower end of the next bag to permit initiation of filling therein.
Problems encountered with known automatic, apparatus for forming packages from a continuous supply of hose-shaped wrapping material include a tendency for articles to bridge within the filling tube which directs the articles into the wrapping material, thereby causing a jam which an operator must clear. Furthermore, in most of the prior art systems, the bag making steps of forming, filling, closing and severing must be performed successively, instead of simultaneously, and thus, the package forming operation is more time consuming. In those systems which do provide simultaneous bag making and filling, complex machinery is generally required for performing such operation.